1. Field of the Invention
The present invention relates to a camera provided with a device for detecting the line of sight of the photographer, thereby detecting the object to be taken.
2. Related Background Art
There have recently been proposed various cameras equipped with a sight line detecting device for detecting the direction of line of sight of the photographer, for use in light metering or in range finding. The methods for detecting the line of sight employed in these proposals are mostly by irradiating the eyeball of the photographer with infrared light and calculating the rotation angle of the eyeball utilizing the Purkinje's first image which is the corneal reflected image and the central position of the pupil or the iris, thereby determining the direction of the line of sight.
Such method of detecting the line of sight is disclosed for example in the Japanese Patent Laid-Open Application No. 61-172552, and its application to a camera is disclosed for example in the Japanese Patent Laid-Open Application No. 2-5.
The method disclosed in the former patent application consists of irradiating the eyeball of the observer with a parallel infrared light beam from a position on the optical axis of an observation optical system and detecting the Purkinje's first image and the center of the pupil, thereby detecting the direction of the line of sight.
However, while the Purkinje's first image can be detected with a light source of a relatively low illumination intensity, the detection of the boundary between the pupil and the iris requires the illumination with a light source of a relatively high illumination intensity. For this reason it has been difficult to efficiently detect the Purkinje's first image and the boundary between the pupil and the iris if there is employed a same light source for both illuminations, particularly a light source providing an illuminating light beam substantially parallel to the optical axis of the observation optical system.